scsi: mvsas: Fix use-after-free bugs in mvs_work_queue

During the detaching of Marvell's SAS/SATA controller, the original code
calls cancel_delayed_work() in mvs_free() to cancel the delayed work
item mwq->work_q. However, if mwq->work_q is already running, the
cancel_delayed_work() may fail to cancel it. This can lead to
use-after-free scenarios where mvs_free() frees the mvs_info while
mvs_work_queue() is still executing and attempts to access the
already-freed mvs_info.

A typical race condition is illustrated below:

CPU 0 (remove)            | CPU 1 (delayed work callback)
mvs_pci_remove()          |
  mvs_free()              | mvs_work_queue()
    cancel_delayed_work() |
      kfree(mvi)          |
                          |   mvi-> // UAF

Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure
that the delayed work item is properly canceled and any executing
delayed work item completes before the mvs_info is deallocated.

This bug was found by static analysis.

Fixes: 20b09c2 ("[SCSI] mvsas: add support for 94xx; layout change; bug fixes")
Signed-off-by: Duoming Zhou <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: stonezdm

drivers/scsi/mvsas/mv_init.c

@@ -124,7 +124,7 @@ static void mvs_free(struct mvs_info *mvi)
 	if (mvi->shost)
 		scsi_host_put(mvi->shost);
 	list_for_each_entry(mwq, &mvi->wq_list, entry)
-		cancel_delayed_work(&mwq->work_q);
+		cancel_delayed_work_sync(&mwq->work_q);
 	kfree(mvi->rsvd_tags);
 	kfree(mvi);
 }